From: Joe Perches <joe@perches.com>
To: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
"H. Peter Anvin" <hpa@zytor.com>, Pavel Machek <pavel@ucw.cz>,
Linus Torvalds <torvalds@linux-foundation.org>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
"Gustavo A . R . Silva" <gustavo@embeddedor.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Kan Liang <kan.liang@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Shawn Landden <shawn@git.icu>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use
Date: Wed, 31 Jul 2019 15:07:50 -0700 [thread overview]
Message-ID: <beb1762387a4132a2bb4c47397b737d77dd88742.camel@perches.com> (raw)
In-Reply-To: <CANiq72kMpP_PSBb0e5wMVNiuYvwSWdR+x_H_tPrEnQ_j1y7X+Q@mail.gmail.com>
On Wed, 2019-07-31 at 22:59 +0200, Miguel Ojeda wrote:
> On Wed, Jul 31, 2019 at 10:02 PM Kees Cook <keescook@chromium.org> wrote:
> > On Wed, Jul 31, 2019 at 08:48:32PM +0200, Peter Zijlstra wrote:
> > > On Wed, Jul 31, 2019 at 11:24:36AM -0700, hpa@zytor.com wrote:
> > > > > > > +/*
> > > > > > > + * Add the pseudo keyword 'fallthrough' so case statement blocks
> > > > > > > + * must end with any of these keywords:
> > > > > > > + * break;
> > > > > > > + * fallthrough;
> > > > > > > + * goto <label>;
> > > > > > > + * return [expression];
> > > > > > > + *
> > > > > > > + * gcc: >https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
> > > > > > > + */
> > > > > > > +#if __has_attribute(__fallthrough__)
> > > > > > > +# define fallthrough __attribute__((__fallthrough__))
> > > > > > > +#else
> > > > > > > +# define fallthrough do {} while (0) /* fallthrough */
> > > > > > > +#endif
> > > > > > > +
> > > > If the comments are stripped, how would the compiler see them to be
> > > > able to issue a warning? I would guess that it is retained or replaced
> > > > with some other magic token.
> > >
> > > Everything that has the warning (GCC-7+/CLANG-9) has that attribute.
> >
> > I'd like to make sure we don't regress Coverity most of all. If the
> > recent updates to the Coverity scanner include support for the attribute
> > now, then I'm all for it. :)
>
> We had this discussion a while ago (October) and the consensus was
> that we would like to wait for a while until all tools were ready to
> use the attribute and everyone's would be happy:
>
> https://lore.kernel.org/lkml/20181021171414.22674-1-miguel.ojeda.sandonis@gmail.com/
>
> Is everyone happy this time around? :-)
Note also that this doesn't actually _use_ fallthrough
it just reserves it.
Patches that convert /* fallthrough */ et al, to fallthrough
would only be published when everyone's happy enough.
next prev parent reply other threads:[~2019-07-31 22:07 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 5:04 [PATCH] net: sctp: Rename fallthrough label to unhandled Joe Perches
2019-07-31 5:35 ` [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use Joe Perches
2019-07-31 9:02 ` Peter Zijlstra
2019-07-31 9:34 ` Joe Perches
2019-07-31 17:14 ` Pavel Machek
2019-07-31 17:51 ` Joe Perches
2019-07-31 18:24 ` hpa
2019-07-31 18:48 ` Peter Zijlstra
2019-07-31 20:02 ` Kees Cook
2019-07-31 20:59 ` Miguel Ojeda
2019-07-31 22:07 ` Joe Perches [this message]
2019-08-01 0:00 ` Miguel Ojeda
2019-08-01 12:25 ` Peter Zijlstra
2019-08-15 18:15 ` Kees Cook
2019-08-15 22:31 ` Kees Cook
2019-09-16 22:19 ` treewide replacement of fallthrough comments with "fallthrough" macro (was Re: [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use) Kees Cook
2019-09-17 22:26 ` Joe Perches
2019-09-17 23:38 ` Kees Cook
2019-07-31 21:01 ` [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use hpa
2019-07-31 23:55 ` Miguel Ojeda
2019-08-01 6:10 ` hpa
2019-08-01 7:52 ` Joe Perches
2019-08-01 12:24 ` Peter Zijlstra
2019-08-01 20:09 ` hpa
2019-08-01 20:26 ` Miguel Ojeda
2019-08-01 20:47 ` Joe Perches
2019-08-02 11:00 ` Neil Horman
2019-08-02 12:34 ` Pavel Machek
2019-08-02 16:09 ` Kees Cook
2019-08-02 16:16 ` Joe Perches
2019-08-04 18:01 ` Joe Perches
2019-08-04 18:09 ` Linus Torvalds
2019-08-04 19:38 ` Miguel Ojeda
2019-08-05 0:39 ` Joe Perches
2019-08-05 1:18 ` Nathan Chancellor
2019-08-05 2:01 ` Joe Perches
2019-07-31 11:19 ` [PATCH] net: sctp: Rename fallthrough label to unhandled Neil Horman
2019-07-31 11:32 ` Joe Perches
2019-07-31 12:16 ` Neil Horman
2019-07-31 16:35 ` Joe Perches
2019-07-31 20:58 ` Neil Horman
2019-07-31 22:23 ` Joe Perches
2019-08-01 10:50 ` Neil Horman
2019-08-01 17:42 ` Joe Perches
2019-08-01 20:48 ` Neil Horman
2019-08-05 11:49 ` David Laight
2019-08-02 17:47 ` Joe Perches
2019-08-02 23:19 ` David Miller
2019-08-02 23:26 ` Joe Perches
2019-08-03 18:01 ` Joe Perches
2019-08-04 19:26 ` Neil Horman
2019-08-02 17:50 ` Neil Horman
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